1. Field of the Invention
This invention relates to a process for making substantially homogeneous copolymers of vinyl pyrrolidone (VP) and N-3,3-dimethylaminopropyl methacrylamide (DMAPMA) of predetermined composition and clear, low viscosity aqueous solutions thereof, for use in hair styling and hair care applications.
2. Description of the Prior Art
Several synthetic polymers containing vinyl lactams are presently being used in cosmetic formulations, particularly in hair care products, to contribute body, set retention and conditioning to such products.
Representative of the art in this field are the following U.S. Pat. Nos.: 3,914,403; 3,954,960; 4,057,533; 4,210,161; 4,586,518; 4,753,793; 4,764,363; 4,834,968; 4,842,850; 4,902,499; 4,906,459; 4,923,694; 4,963,348; 4,983,377; 5,011,895 and 5,015,708; and WO 91/15186; WO 91/15185; EPO 0412704A2; EPO 0412707A1; and JP 57126409.
Generally these synthetic polymers were made by a "one-pot" polymerization process in which selected amounts of the several monomers were reacted together. The composition of these one-pot polymers was considered as being the same as the composition of the charged monomers. However, in reality, such a polymerization process can provide only a mixture of polymers of various compositions, and, additionally, an indeterminate amount of homopolymers and undesired copolymers.
Accordingly, it is an object of this invention to provide a process for making substantially homogeneous copolymers of vinyl pyrrolidone (VP) and N-3,3-dimethylaminopropyl methacrylamide (DMAPMA).
Another object of this invention is to provide a clear, low viscosity aqueous solution of homogeneous copolymers of VP and DMAPMA, in a compositional range of 20-99% VP and 1-80% DMAPMA, preferably 50-95% VP and 5-50% DMAPMA, and most preferably about 80% VP and 20% DMAPMA, at a solids level of 5-20%, preferably about 10-15%, by weight of the solution, having a viscosity of about 5,000 to 80,000 cps, preferably about 10,000 to 70,000 cps.
Still another object herein is to provide clear, low viscosity aqueous solutions of substantially homogeneous copolymers of VP and DMAPMA in a predetermined compositional range and at a selected solids level, which, upon formulation into hair styling compositions, will provide enhanced conditioning, fixative and hair holding properties for the user.